WOW! Talk about nitpicking and blowing something out of proportion.
BOTH ways of spelling "center" are correct.
According to the Oxford English Dictionary, either spelling is perfectly fine:
I. The centre of a circle, of revolution, of centripetal attraction; and connected uses.
1. a. The point round which a circle is described; the middle point of a circle or sphere, equally distant from all points on the circumference.
c1374 CHAUCER Boeth. IV. v. 132
e sterres of arctour ytourned neye to
e souereyne centre or point.
c1391
Astrol. I. §4.
c1400 MANDEVILLE xvii. 185 Aboute the poynt of the gret Compas, that is clept the Centre..Alle the Lynes meeten at the Centre.
1413 LYDG. Pylgr. Sowle I. iii. (1483) 4 The Centre of the erthe was wonder derck.
1570 BILLINGSLEY Euclid XI. xiv. 316 The centre of a Sphere is that poynt which is also the centre of the semicircle.
1591 MORLEY Introd. Mus. 18 His signe is a whole cirkle with a prick or point in the center or middle, thus
.
1613 R. C. Table Alph. (ed. 3),
Centre, middest of any round thing or circle.
1651 HOBBES Leviath. IV. xlvi. 375 The center of the Earth is the place of Rest.
1683 SALMON Doron Med. I. 91 From the Center to the Circumference.
1774 M. MACKENZIE Maritime Surv. 23 The Lines..will intersect each other in..the Center of the Circle.
1822 J. IMISON Sc. & Art I. 15 They are all drawn towards the center of the earth.
1879 LOCKYER Elem. Astron. vii. xli. 239 A circle is a figure bounded by a curved line, all the points in which are the same distance from a point within the circle called the centre.
b. fig.
1600 SHAKES. Sonn. cxlvi, Poore soule the center of my sinfull earth.
a1631 DONNE Poems (1650) 7 This bed thy center is, these wals thy spheare.
1836 EMERSON Nature v. Wks. (Bohn) II. 157 The moral law lies at the centre of nature, and radiates to the circumference.

ccasion9: If you use the Canadian, or Brit, spelling of, say........colour....as opposed to "color"...spellcheck jumps on ya.
Were they flying the Canadian flag or the stars and stripes on the building??
Usually, stupidity trumps literacy, especially when dealing with the armed forces.
:ky:
Why "spellcheck jumps on ya" is because spellcheck is from Microsoft, a USA company. lol
(That's the online version of the OED one actually has to pay for that I quoted the definition from. I refuse to scan, copy and paste the hardcopy version.)
You want to nitpick about a word? Try the pronunciation of "kilometer". Hubby and I both learned the pronunciation was "KILL o meter" and since Turdeau inflicted French on us concerning everything language-wise, some people have been using "ki LOM eter". Excuse me but do they also say "ki LOG ram", ki LOP ascal", ki LOL iter", ki LOT onne? :roll: