Is it possible for an opamp to oscillate at a frequency greater than its GBP?
Some Class AB power amplifiers use a composite PNP/NPN transistor pair to drive current on the low-side swing. LM380, and your TL3141 use this topology. For the LM380, appnotes caution that 5-10 MHz oscillations can be experienced, known to audio insiders as "low-side fuzzies". A Zobel network is suggested as a cure (A series RC from output to ground). Good high-frequency power-supply bypassing can help too.




EDIT: From "Audio HANDBOOK National" (1976),


  ...The classic class B is merely a PNP and NPN capable of huge
  currents but since the IC designer lacks good quality PNP's, a number
  of compromises results. Figure 4.1.4b shows the bottom side PNP
  replaced with a composite PNP/NPN arrangement. Unfortunately, Q2/Q3
  form a feedback loop which is quite inclined to oscillate in the
  2-5MHz range. Although the oscillation frequency is well above the
  audible range, it can be troublesome when placed in proximity to an RF
  receiver. Among the stabilization techniques that are in use, with
  varying degrees of success are:
  
  
  Placing an external RC from the output pin to ground to lower the gain of the NPN. This works pretty well and appears on numerous data
  sheets as an external cure.
  Utilizing device geometry methods to improve the PNP's frequency response. This has been done successfully in the LM377, LM378, LM379.
  The only problem with this scheme is that biasing the improved PNP
  reduces the usable output swing slightly, thereby lowering output
  power capability.
  Addition of resistance in series with either the emitter or base of Q3.
  Making Q3 a controlled gain PNP of unity, which has the added advantage of keeping gain more nearly equal for each half cycle.
  Adding capacitance to ground from Q3's collector.
  
  
  These last three work sometimes to some degree at most current levels.








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