Light controller relay out, new controller now breaker trips after getting hot...

I just had to replace my 8 light controller from sentinell, non stop for 3 years. New controller is exactly the same but few weeks later the breaker is tripping 20-30 minutes into lights on. I have a 50 amp breaker feeding the hph-8 with only 4000 watts connected. Didnt trip when I first installed it, and being an electrician Im assuming its the breaker. Tomorow I will replace this breaker, I turned off two lights just in case, I dont like the feel of the 50 amp breaker when it trips. Im looking for some reassurance, getting high can make me doubtful sometimes

Is the 50A two-pole breaker getting hot, could be faulty breaker, I would pull the breaker and check the bus, it may be oxidized. Is it a Federal Pioneer breaker.