Sticky bottom bracket cable guide
 

After my bike was locked up on a bike rack all day, I hopped on and the first time that I needed to change chainrings (to go uphill) I pushed my bar-end shifter but the FD didn't shift for a second or two. I ended up getting dinner on the way home and remembered that I still had something to do at school so I circled back and being aware of this new issue, I put my bike up in one of the public bike repair stands to see what the problem was. I moved the FD with my hand by gripping it and pushing it back and forth, I couldn't detect any unusual resistance. Then I pulled on the cable immediately in front of the bottom bracket cable guide and sure enough the same behavior, it was sticking. As far as I can tell, something is causing the FD cable to bind-up in the BB cable guide. Looking more closely, I could see that were were little plastic shavings in the immediate area consistent with the material that the BB cable guide is made of. I have die-pulled stainless cables throughout so apart from Teflon coated cables, I don't know of anything that offers less friction. The bike is only one year old and has been ridden something like 1500 miles. I have never heard of this issue before and don't know what to do apart from just replacing the guide. I know it's a cheap part, but I don't want to deal with re-running FD and RD cables if I don't have to. Please advise.

Perhaps a little grease applied where the cable runs through the guide will help. You might also check to be sure that there is not any grit embedded in the plastic.

Don't use grease as it will attract dirt, causing more problems. Use dry chain lube or silicone spray. I suspect you have more of a problem than just the cable guide, check it out closely, the guides generally last a long time.