In 2010, I flew from Denver to Minneapolis. It was a visit during which, I would be riding a loaned bicycle, so I brought a multitool should I need to do some roadside repairs on the loaner. On my flight there, I had plenty of time to go through security and if the multitool (which had a 2" knife blade) was not allowed, I could go check the bag it was in. I went through security without a hiccup.
Landed in Minneapolis, and went to check with security, since I wouldn't have such a time window on my return flight, and wanted to see if I would need to check the bag with the multitool in it or if it would be allowed. I went up to the security station and politely asked the TSA agent if this would be allowed. I had it in my hand as I approached. The knife blade wasn't visible but it was obvious that it was a bicycle multitool. I asked if it would be allowed. A fellow agent came over in the middle of my explanation, and started to ask some questions about the tool.
The first agent sort of waved his hand and said "It's ok, it's a bicycle multitool. It has wrenches and screwdrivers, right? You should be fine."
To which i responded "Well, it does have a 2" knife blade on it, in case you need to cut something."
At this point, the agent stiffened up, looked around and in a very serious voice said "Sir? You have a knife on your person? How did you get into this secure area? You need to leave this secure area immediately or..." and then went into this official sounding tirade.
I tried restating my question, but you'd think I had threatened to stab the guy. I checked the bag on the return flight, but it turns out they didn't like the burly bicycle lock in my check bag, either. As if a big chain would be a threat in the belly of the plane...