The is a "finger strainer" at the outlet from the fual tank into the fuel line which is entirely capable of exculing the chain. Were the chain actually block a portion of the fuel line opening, enough fuel would still get through that you would not notice a problem. It would not be possible for the chain to get anywhere harmful into the fuel system, it would not fit down the fuel line.
This does warrant rectification by a suitably training maintainer - it is definately not do it yourself work.
If I needed to fly a Cessna in this condition, I would not hesitate to do so. I am not your regulator though. Nice going considering that there may be a problem, and asking advice. Many pilots would not have bothered. You have demonstrated the right attitude toward safe flying!
This is the design standard to which the 152 was built:
3.448 Fuel tank outlet
The fuel tank outlet shall be provided with a screen of from 8 to 16 meshes per inch. If a finger strainer is used, the length of the strainer shall not be less than 4 times the outlet diameter. The diameter of the strainer shall not be less than the diameter of the fuel tank outlet. Finger strainers shall be accessible for inspection and cleaning.
Cheers, Pilot DAR