question about MH ballast and new bulbs

[howdy20012002]

I have a 6 foot coralife 150 watt fixture.
I just changed the bulbs and have noticed that the ballast now run significantly hotter -
I actually popped the powerbar and had to replace it.
I had previously been running the same thing with the old bulbs for a couple of months with no problems.
is this norma?
have others noticed a difference in new bulbs verses old bulbs?
thanks in Advance
Neal