Odds of NFL first half total odd or even.

I've seen this prop at a few books so i thought i'd try and figure the odds. I did queries on g.sportsdatabase.com. For even I got 3825 games and for odd I got 3125 games for a 54.79% chance of even. I look up only games after 2006 and the results were 54.00%. Using that figure a fair line would be -117. I see at one book -110 odds on all the evens. I was thinking low scoring games would be more weighted towards one side but could not find any evidence of such. I just recently discovered that database so i'm not sure of it's accuracy but as far as I can tell it is. I feel maybe i'm missing something. Seems like books wouldn't gaff a line that's easy to look up, but if not it seems like a nice little ~3% edge for a no brainer play.