Trust me, you have hit a glitch in the language:
Consider the following examples:
1) It was the third time I had eaten flaki.
Fine
2) It was the last time that I had flaki.
Also, fine.
3) That was the last time that I had been stupid.
Hmmm - sounds a little unnatural.
4) That was the last time I had been to my uncle's home.
As above - but slightly less so.
The problem with the 'ordinal time clause + past perfect rule' is that is breaks down when we are talking about states and actions which are expressed with the P.P form of the verb 'to be'. There are numerous contradictions in English grammar which are very difficult to account for.
Again, this is not to say that your sentence is incorrect, rather I would say that it includes the use of a structure which is not necessary for the message being expressed. In my opinion, it is similar in idea to using 'out-of-date' reported speech in contexts where it is not really necessary or desired.
Please don't take this as a criticism in any way. I didn't want to cause any problems, your 'good teacher' remark was a little uncalled for.
Also, Pakk - if you google something in order to check its accuracy, please ensure that you use the accurate phrase, check my post against yours.
Richie :)
www.newspeak.pl