Why do people say Joe was the one to nurse Pip back to health when Herbert was the one to nurse Pip when they were discussing Estella's parentage in Great Expectations?

In Great Expectations, Joe mentions to Pip that it was he who nursed him back to health, but this is inaccurate. It was actually Herbert Pocket who took care of Pip when he was ill. Joe's confusion may stem from a desire to take credit for Pip's recovery out of affection for him, or it may be a simple mistake in his memory.