It is perfectly normal behavior.
It's called bingeing.
You read one, like it, and go for more. And keep going until the mood changes or something else catches your eye. And since we now operate in an economy of abundance with ample supply of good, cheap books, it is easy to keep on bingeing.
You are not alone.
It is, in fact, the emerging new normal for avid readers. You find a new author or genre you like and you go back for more. And if the author has a deep backlist...
(When I was in college Ballantine reissued the entire Tarzan canon over a period of months so I had me a summer of Tarzan when I binge-read the entire series back-to-back-to-back.)
One of the least acknowledged effects of the online pbook and ebook disruptions is the changes they've fostered in consumer shopper behavior. Bingeing is one such change.
Another is the decline of hoarding. Where once consumers shopped based on what was available on the shelves and were trained to buy on sight anything that seemed interesting because it might not be available a month or even a week later, nowadays the expectation is that a book, once sighted, will be *easily* available indefinitely whether new, used, or in ebook form. So the pressure to pounce on sight is diminished.
Earlier in the mainstreaming of ebooks these ingrained habits led to hoarding of free books but over the past few years readers have been moving towards wishlisting and on-demand buying. Some of the reported decline in ebook sales is probably people wishlisting new releases and making their way through their hoards.
Other behavioral changes will emerge.