Supplying main in grid.arrange throws "only 'grobs' allowed in "gList""

If you supply a title in grid.arrange you get the error

R> grid.arrange(p1, p2, ncol=2, main="My Title")
Error in gList(list(grobs = list(list(x = 0.5, y = 0.5, width = 1, height = 1,  : 
  only 'grobs' allowed in "gList"
In addition: Warning messages:
1: In grob$wrapvp <- vp : Coercing LHS to a list

here is my version info:

platform       x86_64-pc-linux-gnu         
arch           x86_64                      
os             linux-gnu                   
system         x86_64, linux-gnu           
status                                     
major          3                           
minor          2.2                         
year           2015                        
month          08                          
day            14                          
svn rev        69053                       
language       R                           
version.string R version 3.2.2 (2015-08-14)
nickname       Fire Safety

and sessionInfo():

R version 3.2.2 (2015-08-14)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Arch Linux

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8   
 [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=en_US.UTF-8       LC_NAME=C                  LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] gridExtra_2.1.0 ROCR_1.0-7      gplots_2.17.0   ggplot2_1.0.1   vimcom_0.9-91   setwidth_1.0-3  colorout_1.0-0 

loaded via a namespace (and not attached):
 [1] Rcpp_0.12.1        knitr_1.11         magrittr_1.5       devtools_1.9.1     MASS_7.3-43        munsell_0.4.2      colorspace_1.2-6  
 [8] R6_2.1.1           stringr_1.0.0      httr_1.0.0         plyr_1.8.3         caTools_1.17.1     tools_3.2.2        grid_3.2.2        
[15] gtable_0.1.2       KernSmooth_2.23-15 gtools_3.5.0       digest_0.6.8       reshape2_1.4.1     bitops_1.0-6       curl_0.9.3        
[22] memoise_0.2.1      gdata_2.17.0       stringi_0.5-5      scales_0.3.0       proto_0.3-10

baptiste / gridExtra

Supplying main in grid.arrange throws "only 'grobs' allowed in "gList"" #25