That happens with mine. The "100" amper kicks off at 103 or so and after a couple minutes it works its way up to 105 or 106. However, it does not fade back down later, but stays right there. Actually, just before it starts to taper it goes up to 106/7 so you can tell it is about to taper.
My Vector chargers show the same thing. After starting, the amps go up a tad in the first few minutes. I figured this was due to the battery electrolyte taking a time to "get going" but I suppose it could also be the charger itself warming up to the task.