It may happened due to migration. but the reason is still weird. you may go with Trim() function as a immediate solution. and try to insert new records and check still the col. gets extra spaces.
If the column holds numeric data only the best way to deal with it is to use a numeric data type.
Based on what I know the engine (even with Compact Edition although I'm not an expert) should trim any trailing spaces when doing a comparison. Are you doing the comparison with SQL or in .NET once you've loaded the data?