Well I visited with the person who has access to the system and saw with my own eyes when the adjustment was made to my time and who had done it.
It was a start time adjustment that was made at the end of the day, after I had already punched out. Turns out the PC system we use to punch in and out doesn't reflect hour changes, so even at the end of the week when the computer said one thing, it was actually 5 minutes less due to the start time adjustment.
I don't believe it was a malicious act or tampering to make hours look better, I just think the PT made the adjustment and didn't think of how it would affect me, given that I was tracking my hours. They're compensating me plenty of extra time to make up the difference.
However, the reason I was so irritated by it was because I've been pursuing a scholarship for school and am required a certain number of hours per week or work hours+community service hours to equal the number of required hours per week. Because I thought I had gotten the required hours for the week, I did no CS work to make up the difference, and thus I have a paycheck reflecting too few hours.
I'm hoping the "Adjust time" on my next check and an explanatory note from my management will correct the issue and I'll still qualify for my scholarship.
Anyhoo, my PT sup's have been made well aware that a lot of us are tracking our hours and they can't just willy-nilly make adjustments to peoples time like that.
And so ends my saga of time card tampering. And we all lived happily ever after ;-)