Is it ok that my cell concentration is different than the expected stock culture

So I had to do dilutions in the lab, and then after I counted the colonies that formed and then determined the concentration of the original culture which was supposed to be 1 x 10^9 cells/mL
but I got numbers like 1.68 x 10 ^7 cells/mL.

Should I be worried, and why or why not?

I might be if you're sure you did all of the calculations correctly, and didn't miss a dilution somewhere. Your answer is off by more than an order of magnitude.