Bloody hot dog! could there be "air pockets" or chambers in a weiner filled with blood? not making this up!

It looked like there was a small "air pocket" or something within the hot dog, which i got from 7-11, i did photograph it as well as recorded it on video. i know hot dogs are pre-cooked and everything, is it still possible to get blood from a hot dog? no, i did not manipulate the hot dog in any way besides adding nacho cheese in it and inserting it in the microwave for 10 sec to heat it up a little.