Tamron 17-50 front focus; send in, replace or ignore?

I've happily been using my Tammy 17-50 2.8 for almost 2 years now. When I started using other lenses, and became more aware of testing their abilities, I noticed it tends to front focus on my 40D. It's not a massive issue to the point where it's unusable, but it can somewhat mess up a critical shot every now and then.
Apart from the front focusing (mostly in tungsten light) it's a really nice lens, and it is very sharp. For low light shooting, I've already started using the 28mm 1.8 and sometimes the 35mm macro, neither of which display this problem...

Since I'm still building my lens line-up, I don't really have the budget to splurge on the obvious choice: Canon 17-55 2.8 IS.

Now I'm kinda thorn on what to do... ignore it? send it in for repair? (out of warranty with european warranty policy I think) or replace it with something else in the normal range?

Any ideas on this?

If it's only in low light that is misses focus then I don't see how the lens is at fault. The camera is the one that has the sensors. After it has got an AF "lock" switch to MF (without re-focusing) and see if the camera still thinks it is in focus.

Besides if you've been happily using it for 2yr now you may as well continue enjoying it.

In case you're considering a body upgrade you can probably fix the issue with microadjust.

I haven't really considered a body upgrade (yet) because my 28mm 1.8, 35mm 2.8, 100mm 2.8 and 50mm 1.8 don't display this behaviour...