I've said this in other threads... I had 4 W's. Only one (in Calculus I) was due to poor performance. The other 3 were all in one semester. I was 18 years-old, 2nd semester of college, and I thought my oh so cool garage manager job @ Fry's electronics was more important.
One of the W's was ridiculous... I was transitioning from pursuing computer networking to pre-pharmacy and @ 12:30AM the day school started (i.e. no classes attended yet), I dropped a tech class and it was still counted as a W! (would not have been if I'd logged in 31 minutes earlier)
The other 2 W's were because my work sked changed to where I could no longer attend my Bio II lab, so I had to drop Bio II since the lab and class were one and the same. I was also taking a Trig class which I was making a C in at the time of dropping (same as you thought, I just wanted a better grade).
As you can see, I did NOT have good reasons at all! Luckily none of this came up with Texas Tech (interviews are closed file), and I was accepted on the first committee round (rolling admissions). I wasn't worried because after that I had a nearly 4.0 GPA the rest of the way throughout, did well on the PCAT and everything else was in order.
The best advice is to contact the school about it and see what they have to say. Personally, I think you did the right thing. If you're making a C in a course, that means you could easily slide to an F if you don't do well on a comprehensive final exam that may be 30-50% of your grade. F's are almost impossible to overcome!