Jobes

My friends pack bowls and roll joints in my car from time to time and sometimes i know that some of the weed they break up ends up on the floor. I have looked around on the floor but cannot find any significant pieces of marijuana but I'm worried that there are very small pieces still no the floor mixed in with the other dirt and pebbles that could possibly alert a k9 unit. They come to my school at random times in the year and they always go through the parking lot.

I'm not worried about other things if they search my car because i don't carry anything weed related to school or in my car but could it be possible for me to get in trouble for just the fact that the dog was alerted but couldn't find anything significant.

If i have the time to, i am going to vacuum out my car. I was jsust wondering if it was worth the effort.