Swelling comb teeth

HI,

I just got a set of Hohner 5 X Marine Band 1896 to begin my harmonica journey with. I have already been teaching myself for a few months on a Hohner Blues Harp but wanted to get more serious and have begun my studies form the beginning with the Level 1 study lessons here.

After only playing my A harp for about an hour and learning tongue blocking study 1,  the teeth of the wooden comb between the 2 and 6 holes have all swollen and are protruding meaning that my tongue is now getting stuck and it makes sliding around the instrument more difficult and causes pain and discomfort.

-Is this normal for this model?

-Is it a defect?

-Am I using too much tongue?

-Should I be returning the instrument?

Thanks in advance for your feedback. 

:)