That does sound like a lamp flicker problem, and it could be the bulb or possibly a problem with the lamp ballast.
If it is just the bulb, they sometimes settle down on their own after some more use. But if I were you I'd ask them to replace the bulb if it doesn't settle down before the 90 day bulb warranty expires. If that doesn't fix it, then they should replace your lamp ballast under warranty.
It sounds like they are giving you pretty good service, so I'm sure they'll sort it out for you.
If it is just the bulb, they sometimes settle down on their own after some more use. But if I were you I'd ask them to replace the bulb if it doesn't settle down before the 90 day bulb warranty expires. If that doesn't fix it, then they should replace your lamp ballast under warranty.
It sounds like they are giving you pretty good service, so I'm sure they'll sort it out for you.