"Gentle introduction" is a pretty typical phrase, meaning more or less that the acceleration curve of learning is a gentle slope. That one doesn't irk me.

"Gentle study" is a bit unusual.

"Gentle ping" or "Gentle nudge", and especially "Gentle reminder", are starting to get a bit more annoying, but I think the intention there is try to convey the opposite of being demanding, but over a textual medium. ¯\_(ツ)_/¯