Oh no! You were are 1150 distinct beers, and now it shows 1120! What happened!
In order to keep our system clean, we merge beers together to keep the system clean. If your number decreased, it's possible that you had checked into the same beers that were merged together. Unsure about why it merged? Double check our Beer Standards and see if any of those reasons match your beers: http://help.untappd.com/kb/beer-guidelines/beer-naming-standards
A key thing to realize is that not every beer on Untappd is considered a new beer. For example if you check-in to a vintage beer (with a Year in it), and check-in to the base beer (without a year in it), there are considered duplicates. Breweries will go in and merge these because there is no difference year to year. Only beers with years on the bottle as part of the logo are accepted.
Want to see what beers you had twice but didn't know it? Check our this link: https://untappd.com/account/merges