Implausibly high surprisal for </s> in ngram model

[rlevy]

This seems wrong: why does we get such a huge surprisal for sentence-end after a period? Input file was:

This is a short sentence.

Command & output:

$ lm-zoo get-surprisals ngram ~/tmp/sentences.txt
reading /opt/srilm/checkpoint/model.lm in binary format
sentence_id	token_id	token	surprisal
1	1	this	5.29354
1	2	is	3.1117
1	3	a	2.92768
1	4	short	9.45191
1	5	sentence	12.0459
1	6	.	3.6674900000000004
1	7	</s>	28.1537

Doesn't happen for GRNN (the -0.0 is a tiny bit funny but probably not worrying about):

$ lm-zoo get-surprisals GRNN ~/tmp/sentences.txt
sentence_id	token_id	token	surprisal
1	1	This	0.0
1	2	is	1.7249029999999999
1	3	a	1.4204510000000001
1	4	short	8.294603
1	5	sentence	10.343164
1	6	.	3.59838
1	7	<eos>	-0.0

[bnicenboim]

isn't it strange that "This" has a surprisal of 0.0 as well??
@rlevy , I haven't seen any reaction in the issues or the chat (https://gitter.im/lm-zoo/community), is this project still alive?