Within the range I wouldn't be too worried. Could be anything, tylenol, etc.. Actually I believe I even read somewhere that ALT levels can be higher during puberty when males see rapid growth. Obviously your not going through puberty, but have you put on alot of muscle lately? Potentially could be it. Adding large quantities of muscle in shorter periods can be taxing on the body.AST 26 IU/L 0-40
ALT 46 IU/L 0-55
46 just seems close to the top of normal, and yes in my younger days I was a very heavy drinker. But, I haven't drank heavily in 5+ years.
Actually after typing that I checked out what WebMD says about ALT (i know, I know, web MD blahblah) But they claim "Strenuous exercise, injury to a muscle, or injections into a muscle." can affect the test. I know you are not injecting, but potentially the first two could have done it.
Bottom line, I think your good to go, but remember, I am not a doctor.