Another Timeline Problem

[kmcbears1]

No: HPFGUIDX 174820

In the Prince's tale we see the progression of memories as Snape ages
- 2 were prior to Hogwart's
- Train to Hogwart's
- Sorting

The problem arises in that we know from one of the early books that 
James saves Severus in their 6th year.  In OOTP, we see from Snape's 
worst memory that calling Lily a Mudblood happen in their 5th year.

In DH, Lily stopped talking to Severus after he called her a Mudblood.

How did the Snape get the memory of talking to Lily after the tunnel 
rescue if Lily didn't talk to Severus after 5th year?

Why was the tunnel memory put out of sequence from past stories?

Thanks to anyone who can explain this 

- KMC