Now What, should this be???

[sphooch]

Hi everyone , just completed the reverse flushing of my 31 roadster and installed the Gano Filter in the upper hose. As i'm looking for leaks I noticed a strange thing happening with my water pump it looks as though the shaft is sliding in and out maybe like a 1/8 in. ?? the pump only has maybe 50 miles on it, its a rebuilt and leakless . is it possible the shaft is moving in and out? what could cause this. if I didn't work on flushing out the radiator I would have never noticed it. Concern would be the fan hitting the radiator and causing big damage. any thoughts on this ?? thanks THE HOOCH