Sony Ericsson Xperia Neo — Xperia Neo Sensitive Screen While Talking

while talking on my xperia neo I noticed an annoying thing: while i was talking and my cheek was pressing against the screen I started dialing numbers on the dialpad WITH MY CHEEK. I couldn't figure out what was going on and the person on the other end of the line was wondering what all the peeping was about

is that NORMAL on new sony ericsson phones?