Welcome to the forum!
Nah, lots of people have had some issues with wifi strength.
I personally use a thing called Wifi Analyzer free from the Market to check for neighbor's signals on the same channel messing things up - that was a killing a buddy of mine. In an airport recently, we were all getting bad wifi reception - but there were three or four services all on one channel. You sweep left-right to see the various screens.
Also, you may be hitting some unlucky nulls.
And also, this is no secret, either the wifi indicator or something else is a little wacky in the stock 2.1 EVO.
They're updating that really soon and it gives a big wifi improvement.
But - maybe try the analyzer for that channel thing, you never know.