I still have yet to add my comments on the episode (I will when I get home!!) but to address your question in as spoiler-free a way possible:
This storyline does have a considerable progression in the book. How far it will be in the show (and in what direction they take it) remains to be seen, however it is not really a spoiler (we ran the news a while back) that Tara Summers was announced as recurring some time ago. I have a feeling that constitutes more than just Alison's brief appearance in Episode 2, so I would expect her to be back at some point. I do agree, though, that dropping it entirely (besides Ty mentioning it in passing last night), only to pick it up several episodes later seems stilted. The best way I can think to make it work would be if Ty hung up on Alison the first time he called, then talked to Tina about it, she discouraged him from contact... but he will change his mind later and go through with it after all. Only that isn't what happened...
Edited at 2013-03-06 01:13 am (UTC)